Create Your Own DIY Lawn Care

Pest Control Superstore | Turf Chest - 10% off + FREE Shipping over $500 →

Safety Products

Choctaw-Kaul

15'' Green Nitrile Gloves

$6.20
View details

Compliance Safety

Ventless Safety Goggles

$4.25
View details

Choctaw-Kaul

Series 122S Zipper Front Coveralls with Hood & Boots

$15.00
View details
Make sure to read the product label of any insecticide you plan to use to find details about the recommended personal protective gear. Typically, it’s advised to wear long pants, a long-sleeved shirt, closed-toe shoes with socks, chemical-resistant gloves, and goggles. If the area has poor ventilation, the manufacturer might suggest wearing a mask or respirator.
Pest Guides Lawn Care Guides

Drain Fly Guide

Identify

Inspect

Treat

Prevent

Drain Fly Identification Guide

What Are Drain Flies?

Drain flies, also known as sewer flies or moth flies, are small flying insects that thrive in areas where organic matter accumulates and decays. Common breeding grounds include sink drains, shower drains, floor drains, and other moist places with standing organic residue. These tiny pests can appear suddenly and multiply quickly. Proper inspection of your drains is essential to confirm that the flies you are seeing are indeed drain flies and not another species.

Call Us

Mon-Fri 9am-5pm ET

Email Our Pros

We’re here to help

Live Chat

Offline. Leave Us a Message

Drain Fly Characteristics

Size

A diagram of drain fly anatomy

  • Drain flies are usually 1/5 to 1/6 inch in length.

Shape

  • Drain flies have 6 legs.
  • They feature one set of fuzzy wings.
  • Drain flies have antennae.
  • When viewed closely, they resemble tiny moths.

Color

  • Drain flies range in color from brown to dark gray or black.

Range

A map showing the range of drain flies in the United States

  • Drain flies can be found in every state across the U.S..

Drain Flies Don't Originate From Pipes

...But That’s Where They Gather

While it may seem like drain flies emerge directly from your pipes, they actually originate outdoors and are drawn into your home by the smell of decaying organic matter within your drains. Drain flies enter through tiny openings in your home.

These flies are most active during the evening and often gather around sinks and drains. Before beginning treatment for drain flies, confirm that the infestation is truly coming from the drains and not another source of moisture or decay. Other small flies, such as fruit flies and phorid flies, are commonly found in kitchens and bathrooms. If the infestation is caused by these pests, the source is likely rotting fruit or mold, and a different treatment method will be required.

Call Us

Mon-Fri 9am-5pm ET

Email Our Pros

We’re here to help

Live Chat

Offline. Leave Us a Message

Step1 How to Inspect a Drain for Drain Flies

Monitor Drain Flies Using Glue Boards
Follow these simple steps to determine if a drain is the source of your drain fly infestation:

  1. Prepare the Area: Before bedtime, thoroughly dry all sinks, bathtubs, and floor drain areas in the suspected rooms.
  2. Set the Trap: Place a strip of clear sticky tape or a small glue board across the center of each drain, sticky side facing down toward the drain. Ensure the drain opening is not completely covered, as this could block the airflow needed for the flies to emerge.
  3. Leave Overnight: Allow the tape or glue boards to remain in place overnight. For a more thorough test, leave them in place over the weekend.
  4. Check for Flies: Inspect the tape or glue boards the next morning. If flies are stuck to the surface, this confirms that the drain is a breeding site for the flies.
  5. Repeat if Necessary: If no flies are found, repeat the test for at least 4 more nights to account for variations in the breeding cycle.

Additional Signs
You may also notice drain flies resting on walls in rooms with infested drains, often clustered near one another.

Products we recommend for Step 1

Pro Tip

Drain flies can sometimes breed in unexpected locations, such as:

  • Under loose floor tiles
  • Inside the tank of an infrequently used toilet
  • Under sinks with leaky pipes
  • Any area with moisture conducive to breeding

If you’ve confirmed the presence of drain flies but the drain inspection reveals no activity, place glue boards around the affected room. Monitor the glue boards daily, and focus your inspection on the area with the highest fly activity to locate hidden sources of moisture.

How to Eliminate Drain Flies

Two Steps to Eliminating Drain Flies

Successfully getting rid of drain flies typically involves a two-step process:

  1. Clean the Drains: Remove the organic debris within the drains that provide breeding grounds for the flies.
  2. Eliminate Adult Drain Flies: Target and eliminate the adult flies to prevent further breeding.

Treatment duration can vary, often taking several weeks to fully resolve. The length of time depends on factors such as:

  • The amount of debris buildup in the affected drains
  • The number of drains infested
  • The severity of the infestation at the start of treatment

By following this guide, you can tackle your drain fly problem effectively and efficiently.

Call Us

Mon-Fri 9am-5pm ET

Email Our Pros

We’re here to help

Live Chat

Offline. Leave Us a Message

Step1 Apply Drain Fly Gel

How to Eliminate Drain Flies Using Drain Gel
Tools or products needed:

  • Drain Gel

Once you’ve pinpointed the drains infested with drain flies, the initial step is to remove the organic debris where the flies are breeding. A drain gel or foam is highly recommended for this task, as these products are specially formulated to break down organic matter buildup in drains, sinks, garbage disposals, and other areas where drain flies thrive.

Instructions:

  • Apply the drain gel or foam to the infested drains during a time when they won’t be used for several hours, such as at bedtime.
  • Follow the product label instructions, which typically recommend treating all infested drains every night for at least 5 consecutive nights.

Products we recommend for Step 1

Pro Tip

For ongoing prevention in areas prone to drain fly issues, apply the drain gel once a week to maintain drain cleanliness and prevent future infestations.

Step2 Treat Adult Flies with a Space Spray

Fly Space Spray Application

Once you’ve started treating the drains with drain gel, the next step is to target and eliminate the adult drain flies. This can be accomplished using a pyrethrin-based space spray.

Products or tools needed:

  • Pyrethrin aerosol spray

Instructions:

  • A space spray involves releasing an aerosol product directly into the air rather than applying it to surfaces. Only pyrethrin aerosols are typically labeled for this purpose.
  • Space sprays are ideal for quickly reducing large populations of drain flies that are actively flying in your space.
  • Follow the product label directions to apply the aerosol spray.
  • Keep in mind that most space sprays require vacating the treated area immediately after application and ventilating the room before re-entry. Refer to the product label for specific re-entry guidelines.

Additional Tips:

  • Any remaining pyrethrin spray can be used for spot treatments or direct applications whenever new drain flies are spotted.

Products we recommend for Step 2

Step1 Drain Fly Prevention Guide

Prevention

1. Maintain Clean and Covered Drains

Drain flies can be prevented by keeping drains clean and ensuring unused drains are securely covered.

  • Weekly Drain Maintenance: Use a drain cleaner gel weekly to prevent the buildup of organic matter in drains. Apply the gel during times when the drain will not be in use, such as before bedtime.
  • Cover Unused Drains: Use drain stoppers or flat rubber covers (available at most home improvement stores) to block seldom-used drains and prevent drain flies from settling and breeding inside them.

Products we recommend for Step 1

Pro Tip

For homes or businesses that frequently experience drain fly issues, consider using an insect growth regulator (IGR) labeled for drain flies. IGRs disrupt the life cycle of drain flies, preventing larvae from maturing into reproductive adults. These products are available in both concentrated liquids and ready-to-use aerosols and can be applied to catch basins and around vulnerable drains.

Next